// 独一无二 
let sym1=Symbol('name')
let sym2=Symbol('name')
console.log(sym1==sym2);//false

// Symbol.for(key)
function setName(obj){
    obj.name='window'
    obj=new Object()
    console.log(obj);
    obj.name='grobal'
    console.log(obj);
}
let person={
    name:'person'
}
setName(person)
console.log(person.name);

// 不可枚举
const myObj={
    name:'myObj',
    age:19,
    [Symbol('hobby')]:'running'
}
console.log(Object.getOwnPropertyNames(myObj));
console.log(Object.keys(myObj));
console.log(Object.getOwnPropertySymbols(myObj));
console.log(Object.getOwnPropertyDescriptor(myObj));
console.log(Object.getOwnPropertyDescriptors(myObj));